Filed of the Invention
The invention is directed to corrosion inhibitors especially those useful in the oil and gas industry and in the drilling profession.
Description of Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
The annual cost of corrosion worldwide was estimated at $ 2.2 Trillion in 2010, which is about 3% of the world's gross domestic product (GDP) of $ 73.33 Trillion (Al Hashem, A. Corrosion in the Gulf Cooperation Council (GCC) states: statistics and figures, in Proceedings of the Corrosion UAE, Abu Dhabi, UAE, 2011). Corrosion can build up in wellbore tubulars and other downhole components causing considerable damage to the life of a well in an oil or gas oilfield. Corrosion mitigations costs the oil and gas industries millions of dollars yearly.
One of the most practical and cost effective approaches in mitigation of aqueous corrosion in oil and gas industry is through use of chemical agents called corrosion inhibitors. In this context, the treatment of mild steel in oilfield corrosive environment, containing corrosive molecules such as H+, CO2, H2S, H2O and Cl−, using organic compounds has resulted in considerable savings to the oil and gas industry.
The development of corrosion inhibitors for the oil industry occurred mainly in 1940s and 1950s (Harrop, D. Chemical inhibition in demanding environment: Assuring continuing asset integrity through best practice deployment. Corrosion Management in Upstream Oil and Gas. Aberdeen, 2004). In the mid-1940s, long-chain polar compounds were shown to have inhibitive properties. This discovery dramatically altered the inhibitor practices in primary production oil and gas wells. It permitted operation of wells, where entire reservoirs would have otherwise to be abandoned because of the corrosivity and volume of water produced along with the hydrocarbons.
In the patent literature, inhibitor composition used in the oil and gas wells include a number of nitrogen-containing compounds, such as amines, imidazolines, amides and quaternary ammonium salts, often in combination with other types of inhibitors, including alkoxylated phosphate esters, intensifiers and surfactants. These inhibitors adsorb on the metal surface by forming a film. Examples of such film-forming inhibitors may be found in the following U.S. Patents and Patent Publications: U.S. Pat. Nos. 7,057,050 B2, 8,741,390, 8,618,027 B2, EP 1457 585 A1, EP 1333108 A2, U.S. Pat. Nos. 3,077,454, 4,209,418, 5,393,464, 5,779,938, US 2011/0040126 A1, and US 2016/0115598 A1.
The basic types of currently used commercial corrosion inhibitors have long chain hydrocarbons (usually C-18), as diamines or imidazolines. Although these inhibitors had met with varying success under demanding conditions encountered in offshore oil production operations, increasing environmental concerns due to their highly toxic natures have put additional constraints on their use (Singh, W. P. Bockris, J. O'M. Toxicity issues of organic corrosion inhibitors: Applications of QSAR model, The NACE International Annual Conference and Exposition, USA, 1996). Toxicity issues of organic corrosion inhibitors: Applications of QSAR model, The NACE International Annual Conference and Exposition, USA, 1996.).
This is due to the fact that the long alkyl chains have been known to increase the toxicity of imidazolines. Furthermore, imidazolines formulations have been shown to aggravate localized corrosion by creating a number of micro-anodes, leading to local anode dissolution (Tan, Y. Mocerino, M. Paterson, T. Organic molecules showing the characteristics of localized corrosion aggravation and inhibition Corrosion Science 53 (2011) 2041-2045). As a result, pitting corrosion occurs on pipelines when imidazoline inhibitors are added to the fluid (Liu, X, Okafor, P. C. Zheng, Y. G. The inhibition of CO2 corrosion of N80 mild steel in single liquid phase and liquid/particle two-phase flow by aminoethyl imidazoline derivatives. Corrosion Science 51 (2009) 744-751).
With these and other objectives in mind, the inventors diligently sought an environmentally friendly, cost-effective, high-performance, easily scalable anti-corrosion composition. As disclosed herein, one way to overcome the problems and drawbacks of conventional corrosion inhibitors is to use novel azoles and polypeptide amino acid formulations having remarkable corrosion inhibiting properties despite the absence of long alkyl chains in their structure. As shown herein, in many embodiments, the azoles and polypeptides selected in this present invention do not have long alkyl chains, are naturally occurring, and are environmentally benign.
Improving the effectiveness and efficiency of oil field corrosion inhibitors by using environmentally friendly compositions, can undoubtedly save the oil and gas industry millions of dollars per year in chemicals and lost production and also protect the environment from pollution. It is an object of the present invention to provide ecofriendly corrosion inhibitor composition which is effective in preventing corrosion of metals in contact with metal surface in aqueous environment commonly found in oil and gas industry even when used in ppm levels.